The present invention relates to the field of heat-curing epoxy resin bodyshell adhesives.
Heat-curing epoxy resin compositions have been known for a long time. An important application of heat-curing epoxy resin compositions is in vehicle assembly, in particular in bonding or in filling cavities in the bodyshell with foam material. In both cases, after application of the epoxy resin composition, the body is heated in a CDC (cathodic dip coating) oven, whereby the heat-curing epoxy resin composition is also cured and optionally expanded into a foam.
For fast curing, usually accelerators or activators are used in addition to heat-activated curing agents for epoxy resins. However, a disadvantage is that most activators or accelerators have a very negative effect on the mechanical properties of the cured epoxy resin. Besides ureas, certain imidazolines are also known in the prior art as activators or accelerators. Thus EP 0 501 074 A1 describes 1-isopropyl-2-phenylimidazoline and U.S. Pat. No. 4,246,394 discloses different imidazolines for use in heat-curing epoxy resin compositions. Finally, U.S. Pat. No. 4,997,951 describes imidazolines which can be synthesized from methyl salicylate. But these imidazolines have certain weaknesses, in particular with respect to activation behavior.